Retrieve AlternateText of ImageButton in DataList on Click in ASP.Net

Respected Sir,

           I am coding one project for my last year project. In this project i have code for seat selection logic. In this I used datalist control and one image button control inside template field. I want to code like,,,

                    when I do click on this image button i want to send this buttons's alt text in DB as seat no. but I could not code for same. 

      If you can help me to code this or do you have any another logic for seat selection in asp.net code?? 

Thanks.

Mahendra.